Challenge the future Delft University of Technology Peter van Oosterom STW User Committee meeting, Oracle, Utrecht, 19 September 2012 Explanation of the STW/NWO project “Vario-scale geo-information”

2 Vario-scale Topographic map series and the art of map generalization Map fragments from different source scales enlarged to same ‘scale’ for content comparision

3 Vario-scale Multi-scale: a good option? Multi-scale databases: often multiple representation drawbacks: redundancy, fixed levels of detail  potential inconsistent Scaleless data structures: single representation with additional structure to access at any level of detail Often also spatial organization (clustering/indexing) Progressive transfer: keep sending more details (compare to raster formats: data pyramids, wavelets)

4 Vario-scale a b c d e f gi j l k h Step 0 Importance(u) = Area(u)*Class-Weight(u) Comp(u,v) = Length(Bnd(u,v)) * Class-Similarity(u,v)

5 Vario-scale a b c d e f gi j l h Step 1

6 Vario-scale a b c d e f gi j l h Step 1 blg

7 Vario-scale m b c f gi j l h Step 2

8 Vario-scale b c f gi j l h m Step 2 blg

9 Vario-scale m b c f n h Step 3

10 Vario-scale b c f h m n Step 3 blg

11 Vario-scale m o p Step 4

12 Vario-scale m p o Step 4 blg

13 Vario-scale q Step 5

14 Vario-scale q Step 5 blg

15 Vario-scale 5 (V)4 (U) 3 (Z)9 (U) 10 (U) 6 (W)2 (Y) 1 (X)7 (Y) 8 (Y) 11 (U) GAP face-tree

16 Vario-scale Resulting tGAP structure

17 Vario-scale Selection of faces overlap search region & Importance = Use tGAP structure

18 Vario-scale tGAP principles 1.Variable scale: ‘near infinite’ amount of levels 2.Base level with most detailed geometry/topology 3.Create links/structure on top

19 Vario-scale Generalized Area Partitioning-tree a ‘3D view’ Vermeij et al proposed topological GAP-tree: edges and faces (with importance range, consider as height)  scale/imp with 3D prisms

20 Vario-scale Support of non-area objects Support for non-area objects fits in tGAP structure: 1.Points: own table with importance range 2.Lines: same but now with reference to BLG-repr. 3.Also combine 2 less important lines in 1 (e.g. after removal of least important branch) This enables: the change from area to line (or point) representation at certain moment. Similar to normal GAP-structure when face is removed, but now it is also introduced in node or edge table (with link).

21 Vario-scale Other generalization operations Consider collapsing of areas in lines (or points) Compute skeleton (medial axis), connect to neighbors P0P0 P1P1 P2P2 P3P3

22 Vario-scale Result fits in tGAP structure (Ai & van Oosterom, SDH’02 more: Meijers, Savino, van Oosterom’12 in preparation) Weighted skeleton

23 Vario-scale tGAP example 1.Collapse road (split area, merge neighbours) 2.Delete forest (merge with farmland) 3.Simplify boundary (between water/farmland) 1 2 3

24 Vario-scale 2D+scale  3D integrated tGAP DAG to 3D structure Parent-child:  neighbour above-below

25 Vario-scale Delta scale  no change at all or local shock

26 Vario-scale Smooth tGAP Remove local shock  no horizontal faces Gradual changes  less vertical faces Resulting polyhedron  representation of single object for all its scales

27 Vario-scale Delta scale  delta map

28 Vario-scale Non-horizontal slice  mixed scale map

29 Vario-scale Non-flat slice  mixed scale map (fish-eye example) x y S=0 S=0.5 source: Harrie et al, 2002, ISPRS Archives 34(4):237–242

30 Vario-scale The highly challenging project goals Semantic aspect (incl. attributes) needs further attention Lower dimension primitives (lines, points) do also fit in the structure, but need further investigations Fast slicing, exploiting coherence between delta scale Include label placement in smooth-zoom Not per se object by object creation (but multiple objects in parallel) Sliver before disappearing Lot of implementing and testing needed (engineering)